Re: [PATCH v1 03/11] perf: Allow for multiple ring buffers per event

Peter Zijlstra
2014-05-08T14:16:32Z

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On Thu, May 08, 2014 at 03:46:36PM +0300, Alexander Shishkin wrote:
> Peter Zijlstra <peterz@infradead.org> writes:
>
> > On Thu, May 08, 2014 at 03:34:17PM +0300, Alexander Shishkin wrote:
> >> Peter Zijlstra <peterz@infradead.org> writes:
> >>
> >> > So the aux_head/tail values should also be in the file space and not
> >> > start at 0 again, similar for the offsets in the AUX record.
> >>
> >> Thinking some more about it: if we keep aux_{offset,size} in userpg,
> >> then it would make sense to have aux_{head,tail} run from 0 to infinity
> >> similar to data_{head,tail}, especially considering that neither data_*
> >> nor aux_* pointers are file offsets anyway.
> >
> > Yeah, this might make it easier. So then the rule is *_offset +
> > *_{head,tail} is the actual file offset into the buffer.
>
> You mean *_offset + (*_{head,tail} % *_size) ?

Indeed I did..

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